1. Field of the Invention
The present invention relates to an adhesive composition and an adhesive sheet, and more particularly to an adhesive composition and an adhesive sheet suitable for a use application of protecting a semiconductor.
2. Description of the Related Art
In recent years, with miniaturization and realization of high performance of electronic devices, a demand for density growth and high integration of semiconductor apparatuses is intensified, and realization of a high capacity and density growth of IC packages are advancing. To connect a semiconductor chip with a substrate, a wire bonding method using a thin metallic wire has been conventionally widely applied, but a flip chip mounting method for forming a conductive protrusion called a bump on a semiconductor chip and directly connecting a substrate electrode with the bump on the semiconductor chip is becoming mainstream in order to cope with the demand for density growth and high integration. In general, in the flip chip mounting method, for the purpose of reinforcement of a connecting portion, improvement of reliability, and others, a gap between the semiconductor chip and the circuit substrate is sealed with a resin. As a resin sealing method, there is generally a capillary underfill method, and this method is carried out by applying a liquid sealing resin composition to one side or a plurality of sides of the chip and utilizing a capillary phenomenon to flow the resin composition into the gap between the circuit substrate and the chip (see Japanese Patent Laid-open (kokai) No. 2007-217708).
As shown in FIG. 1(II), such a capillary underfill method requires a step of, e.g., applying a flux 21 to a circuit substrate 20 (a step (a)), a step of mounting a semiconductor chip 22 having bumps 22a formed thereon onto the circuit substrate 20 (a step (b)), a joining step of joining and connecting the semiconductor chip 22 to the circuit substrate 20 by using the flux 21 to form joint portions 23 for the semiconductor chip and the substrate (a step (c)), a flux cleaning step (a step (d)), a step of applying a liquid sealing resin composition (underfill 24) to one side or a plurality of sides of the semiconductor chip 22 (a step (e)), a step of flowing the liquid sealing resin composition (the underfill 24) into a gap between the circuit substrate 20 and the semiconductor chip 22 by utilizing the capillary phenomenon (a step (f)), and a sealing step of hardening the liquid sealing resin composition (the underfill 24) used for filling to provide hardened underfill 24a and sealing step for performing resin sealing (a step (g)) is required, and hence this method is complicated, and the cleaning liquid waste disposal is required. Further, since the capillary phenomenon is used for the resin sealing at the step (f), a sealing time is increased, and a problem may occur in productivity.
Consequently, as a method for solving these problems, there is disclosed as method for directly attaching a semiconductor adhesive film made of an acrylic resin composition containing a compound having a flux activity to a semiconductor chip and using the chip in this state (see Japanese Patent Laid-open (kokai) No. 2009-239138). In this process, the flux is not used, the semiconductor adhesive film is bonded to a functional surface of the semiconductor chip, the semiconductor chip is joined and connected to the circuit substrate (a joining step), and the semiconductor adhesive film functions as not only the flux but also a resin sealant after the joining step. Therefore, in the capillary underfill method shown in FIG. 1(II), the step of, e.g., applying the flux 21 to the circuit substrate 20, the flux cleaning step (the step (d)), the step of applying the liquid sealing resin composition (the underfill 24) to one side or a plurality of sides of the semiconductor chip 22 (the step (e)), and the step of flowing the liquid sealing resin composition (the underfill 24) into the gap between the circuit substrate 20 and the semiconductor chip 22 by utilizing the capillary phenomenon are no longer required. As a result, the complication of the steps in the capillary underfill method can be improved. However, productivity can be improved as compared with the conventional capillary underfill method, but an acrylic resin, which is especially an acrylic resin containing acrylic nitrile, is used in Japanese Patent Laid-open (kokai) No. 2009-239138, and hence there is a serious problem that insulation reliability (migration resisting properties) under high-temperature and humidity conditions is poor. Therefore, in the method disclosed in Japanese Patent Laid-open (kokai) No. 2009-239138, the purpose of, e.g., reinforcement of the connecting portion in flip-chip mounting or improvement of reliability is not perfectly achieved. Therefore, development of an adhesive composition for a semiconductor apparatus that exhibits excellent adhesion properties when pressure-bonded and has excellent connection reliability and insulation reliability when hardened has been strongly demanded.